This invention relates to apparatuses for the casting or injection-moulding of footwear soles in two or more layers of polyurethane, preferably with simultaneous moulding to an upper of the footwear article, the sole parts being produced and connected with one another and if necessary with the footwear upper in successive casting of injection-moulding steps.
Various methods and apparatuses are known for the production of two-layer, two-colour shoe soles with simultaneous moulding to a shoe upper by casting or injection-moulding. According to German Patent Specification No. 2,022,118, a sole layer facing the shoe upper is moulded to the latter in a first injection-moulding action, and then, the outer sole layer forming the tread surface is moulded to the first layer.
Alternately, it is also known from German Patent Specification No. 2,241,493 to produce the sole layers in the converse sequence wherein the sole layer remote from the shoe upper is first produced, and then the sole layer extending between the layer and the upper is produced by casting and subsequent moulding.
In the above prior art the two-layer sole is in each case formed so that a drawn-down sole edge of the layer facing the shoe upper extends approximately to the plane of the tread surface. The side face of the outer or lower sole layer is thus completely covered by material of the intermediate sole layer. The side face of the sole thus imparts the impression of a one-piece and single colour configuration.
The invention is concerned with multi-part mouldings, especially shoe soles, in which the individual sole layers are not covered by one of the utilized materials but are deliberately and visibly defined from one another. A clear, unblurred and defect-free limitation of two sole parts, especially of different colours, is not however readily achievable in practice.